Using the Raspberry Pi for a multimedia center on your boat

Problems with the Display Screen

Setting up OpenELEC for DVB-T is relatively trivial in comparison to setting up the hardware. The initial configuration proved fairly straightforward with one exception. The display screen overlay, which is actually a relic from the past, posed some problems. When applied to television screens that used to work with tubes, the term overlay referred to darkened regions of an image. The overlay plays a special role in analog video signals that are played on digital display devices. When the image comes from a digital source, the overlay has no role because the TV should not use it.

However, the Grundig TV applied a mask to the displayed image that came directly from the HDMI port of the Raspberry Pi. This approach had some undesired side effects. The Full HD resolutions sent from the Rasp Pi appeared misshapen and blurry on the display screen. All attempts to resolve the problem on the Rasp Pi side failed. In the end, the manual for the Grundig TV proved helpful. The manual describes the steps necessary for turning off the overlay via the device service menu. Once the overlay was turned off, the picture was in focus and otherwise perfect. The lesson I learned from the hours of trying to fix the problem was to first look in the manual for the TV before proceeding with the configuration.

OpenELEC and DVB-T

Some moments of tension arose after connecting the DVB-T stick to the Rasp Pi. The command dmesg provided confirmation that OpenELEC recognized the device and that the suitable driver for DVB-T had loaded, but I had to troubleshoot some problems with the signal processing.

The first step was to activate the Unofficial repository for additional software. This is where OpenELEC puts the components that should be compatible with the system. However, the project does not guarantee that these components will actually work. After enabling the repository for the additional software, you should find and activate Tvbackend in the configuration menu. The module runs in the background and is responsible for decoding the DVB signal.

The corresponding module on the client side is called Tvheadend. The module has its own web interface, which is where you should set up the DVB-T adapter, paying particular attention to the DVB mode that the adapter should use. Then comes a channel search and exporting of the channels that have been identified into the OpenELEC menu, where an additional menu option TV will then appear.

As an aside, it is interesting to note that the Grundig TV is capable of decoding DVB-T signals by itself, but the tripleStick ended up having significantly better performance, especially with the complications caused by the motion of the boat.

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